This invention relates to the structure and manufacturing of electronic devices.
Transceiver technology has evolved over the decades from the use of wires, electro-mechanical, components, and machined waveguide structures to the use of coax and thick film/thin film microstrip/stripline-based circuitry. But even with this evolution, the recent proliferation of, and resulting stiff competition among, wireless communications products have led to price/performance demands on transceivers that conventional technologies find difficult to meet. A transceiver conventionally comprises a protective enclosure, an antenna, xe2x80x9cfront endxe2x80x9d filters (e.g., a duplexer), amplifiers and other transceiver circuitry, and connectors and cabling. The most expensive components typically are the antenna, the filters, and the amplifiers.
Conventional antenna and filter manufacturing techniques use a variety of precision-machined components, which are manually or automatically assembled and aligned and then assembled onto printed-circuit boards. High-volume manufacturing techniques have been used to reduce the costs of some conventional antennas and filters. However, these techniques do nothing to improve the performance of these components, nor do they improve the costs of low- and medium-volume components. Moreover, they do nothing to reduce the amount and the cost of cabling and connectors between the antenna and the filters; these components not only add to the cost of the transceiver, but also reduce the overall performance thereof. Others have sought to reduce the cost of antennas and filters at the expense of other parts of the transceiver; essentially, by shifting the cost to these other parts. One example is replacing standard front-end components with ones that have a better performance to make up for the poor performance of cheap antennas and filters, such as replacing the low-noise pre-amplifier (LNA) with one that has a lower noise figure and a higher dynamic range (i.e., higher 1-dB compression or higher third-order intercept (TOI)), or replacing the output power amplifier (PA) with one that has a higher output power. The problem with these approaches is that they merely transfer the cost to another area of the transceiver without substantially lowering the cost of the transceiver as a whole. In fact, they generally increase the complexity and the cost of the transceiver.
The problems faced by transceiver technology illustrate the problems being faced by the electronics industry as a whole: the downward pressure on prices, and hence costs, of electronic devices accompanied by rising expectations for their performance. What the art as a whole seeks are simpler and cheaper manufacturing techniques for electronic devices that also improve, or at least do not degrade, the devices"" performance.
This invention is directed to solving these and other problems, disadvantages, and needs of the prior art. Generally according to the invention, a new physical design is provided for electronic devices. The design is particularly advantageous for radio frequency (RF) devices, such as radios, that include circuit components which may require electromagnetic shielding. Generally, the design is a stacked assembly made of a plurality of conductive portions. Some are planar, each defining a plane. Others are wall portions, each defining a closed wall within a plane. The planar portions and the wall portions are positioned side-by-side with each other along an axis, with their planes being substantially perpendicular to the axis. The planar portions and the wall portions alternate with each other, and are affixed to each other. Each portion may be a distinct unit, or a planar portion and a wall portion may form a single unit, e.g., one formed from a single sheet of conductive material. At least some of the portions carry electrical components all of which are interconnected with each other. At least some of the portions form at least one electromagnetically isolated chamber that encloses at least some of the electrical components. Illustratively, the design is a multi-layer, stacked assembly of a plurality of pan-shaped conductive units or layers, at least some of which carry electrical components. All of the units are oriented (face) in the same direction, are stacked one on top of another, and are fixedly attached to each other, e.g., by weld, solder, adhesive, or mechanical attachment such as rivets, screws, bent tabs, or twisted tabs. Adjacent units advantageously define electromagnetically isolated chambers. The electrical components carried by the different units are electrically connected to each other.
The stacked assembly is easy to assemble: At least some of the plurality of conductive planar portions and the plurality of conductive wall portions are caused to carry electrical components, the portions are arranged alternating with each other and positioned side-by-side with each other along an axis with their planes being substantially perpendicular to the axis, and the portions are affixed to each other so that all of the electrical components are interconnected with each other and at least some of the portions form at least one electromagnetically isolated chamber that encloses at least some of the electrical components. In the illustration embodiment, the electrical components are defined by, e.g., mounted on or formed in, at least some of the units, the units are stacked one on top of each other such that they all face in the same direction and are attached to each other, and the electrical components carried by different units are electrically connected to each other. Preferably each unit is made of a single unitary member (e.g., a metal sheet) that is shaped (e.g., bent, or folded) to create the pan shape. Alternatively, each unit is made in two parts: a planar member (e.g., a flat sheet) that forms the bottom of the pan shape and a closed wall member that forms the sides of the pan shape, and the two parts are then fused together. Preferably, low-cost manufacturing techniques, such as metal stamping, cutting, and/or etching, are used to form the electrical components, (e.g., antennas, filters) in the units. Preferably, the stacked units are attached to each other via low-cost fusing techniques such as soldering, welding, or adhering with adhesive. Significantly, adequate performance and shielding can be achieved with the use of non-conductive (structural) epoxy, which is fast and cheap. Further preferably, interconnection between the electrical components defined by different units are made by flanges that are defined by the units and that extend between the units, or even by edges of the wall members, if there is no lip.
In an illustrative example described further below, the stacked assembly is used to implement a transceiver. The transceiver is constructed as a stacked assembly of its constituent parts, with some parts performing xe2x80x9cdouble dutyxe2x80x9d in the assembly, thereby decreasing the transceiver""s complexity and cost. For example, the antenna and xe2x80x9cfrontendxe2x80x9d filters of the transceiver are integrated into the assembly in such a way that a unit that forms shielding of the filter also forms a ground plane of the antenna, thereby decreasing transceiver complexity and cost. The circuit board that carries the transceiver circuitry is also integrated into the structure such that a unit that forms the shielding of the filter also forms both a mount for the circuit board and a shield for the circuitry.
Benefits that may be obtained through the invention include lower-cost, and higher-performance devices than are obtained through conventional designs, fewer parts and fewer process steps involved in fabrication than are obtained with conventional designs, easier assembly of the device, and elimination of discrete connectors and cabling between layers.
These and other features and advantages of the invention will become more apparent from the following description of an illustrative embodiment of the invention considered together with the drawing.